In a biochemical pilot study of six controls and six patients with a possible diagnosis of early infantile autism, we found that none of the normal children excreted bufotenin in 24-hour urine collections. In contrast, urinary collections of the six children with a possible diagnosis of early infantile autism were positive for bufotenin in five of the six patients. In the proposed investigation, we wish to test these results by placing ten children with a clinical diagnosis of early infantile autism and 20 controls (two controls for each patient matched for age, height, weight and sex) in a hospital ward where each will receive a rigorous diet calculated according to his age, height and weight. The normal controls will be divided into two groups of 10, each group being subjected to same conditions as the patients. In the urine we shall look for dimethyltryptamines, N,N-dimethyltryptamine, bufotenin and 5-methoxy-N,N-dimethyltryptamine. In the blood we shall study in all individuals the activity of N-methyltransferase using N-methyltryptamine as a substrate, for this enzyme can change the naturally accurring products of tryptophan metabolism in the brain into psychotogenic N,N-dimethyl compounds. Methods (behavioral): Dr. R. L. Jenkins will select an follow the clinical courses of the subjects. Please see "Methods of Procedure" "Behavioral" under "Research Plan" section. Methods (biochemical): Two-dimensional thin-layer and gas-liquid chromatographic methods as well as gas chromatographic-mass spectrometric methods will be used for the quantitative determination of the dimethylated tryptamines in urine and of N-methyltransferase activity in serum in the case of each individual.